The present invention relates to an apparatus and a method to objectively measure sensory discrimination thresholds by delivering a time and pressure controlled air puff to the upper aero digestive tract, including, for example, the oral cavity, pharynx, or supraglottic larynx of a patient.
Within this application several publications are referenced by arabic numerals within parentheses. Full citations for these and other references may be found at the end of the specification immediately preceding the claims. The disclosures of all of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.
There is a dearth of published studies of supraglottic and pharyngeal sensation in normal healthy controls, in the elderly, or in those who have suffered from a cerebrovascular accident (CVA). One of the primary problems with measuring sensation in this region (the area innervated by the superior laryngeal nerve) is the presence of the gag reflex and the relative inaccessibility of this area in awake individuals. These obstacles preclude standard sensory discrimination tests such as static and moving two point discrimination, vibratory testing, and stereognosis (1).
Knowledge of pharyngeal and supraglottic sensory discrimination thresholds is particularly important since hypesthesia or anesthesia in this area of the head and neck can cause severe dysphagia and an increased frequency of aspiration. Dysphagia and aspiration are commonly seen in the elderly (2), in those who have suffered a stroke (3), and in patients who have had ablative cancer surgery of the pharynx and larynx (4, 5) and/or loss of cranial nerves. The development of treatment modalities which address the sensory deficits in the pharynx and larynx is dependent upon defining and quantifying the sensory deficits in this region. The first step towards this goal is to establish normal thresholds for sensory discrimination.
However, as of yet, it appears that no one has been able to achieve this first step of measuring pharyngeal sensation in healthy control subjects, much less than in stroke patients with dysphagia. In other medical fields, air pulse stimulation of the cornea, or pneumatic tonometry has been used by ophthalmologists in order to measure intraocular pressure (6). Sensory discrimination testing using this technique, however, was not applied to the cornea. Air pulse stimuli have also been used as a natural stimulus to study the mechanisms whereby somatosensory systems analyze sensory stimulus patterns (7, 8). Furthermore air pulse stimuli have been shown to be an extremely sensitive and reliable method of determining sensory discrimination thresholds in the upper extremity of man (8, 9). However, it appears that no previous method of sensory testing of the upper aero digestive tract, including specifically the oral cavity, supraglottic larynx, or pharynx has been described.